/*
  probe.c - code pertaining to probing methods
  Part of Grbl

  Copyright (c) 2014-2015 Sungeun K. Jeon

  Grbl is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  (at your option) any later version.

  Grbl is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with Grbl.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "grbl.h"

// Inverts the probe pin state depending on user settings and probing cycle mode.
uint8_t probe_invert_mask;


// Probe pin initialization routine.

void probe_init() {
    PROBE_DDR &= ~(PROBE_MASK); // Configure as input pins
#ifdef DISABLE_PROBE_PIN_PULL_UP
    PROBE_PORT &= ~(PROBE_MASK); // Normal low operation. Requires external pull-down.
#else
    PROBE_PORT |= PROBE_MASK; // Enable internal pull-up resistors. Normal high operation.
#endif
    // probe_configure_invert_mask(false); // Initialize invert mask. Not required. Updated when in-use.
}


// Called by probe_init() and the mc_probe() routines. Sets up the probe pin invert mask to 
// appropriately set the pin logic according to setting for normal-high/normal-low operation 
// and the probing cycle modes for toward-workpiece/away-from-workpiece. 

void probe_configure_invert_mask(uint8_t is_probe_away) {
    probe_invert_mask = 0; // Initialize as zero.
    if (bit_isfalse(settings.flags, BITFLAG_INVERT_PROBE_PIN)) {
        probe_invert_mask ^= PROBE_MASK;
    }
    if (is_probe_away) {
        probe_invert_mask ^= PROBE_MASK;
    }
}


// Returns the probe pin state. Triggered = true. Called by gcode parser and probe state monitor.

uint8_t probe_get_state() {
    return ((PROBE_PIN & PROBE_MASK) ^ probe_invert_mask);
}


// Monitors probe pin state and records the system position when detected. Called by the
// stepper ISR per ISR tick.
// NOTE: This function must be extremely efficient as to not bog down the stepper ISR.

void probe_state_monitor() {
    if (sys_probe_state == PROBE_ACTIVE) {
        if (probe_get_state()) {
            sys_probe_state = PROBE_OFF;
            memcpy(sys.probe_position, sys.position, sizeof (sys.position));
            bit_true(sys_rt_exec_state, EXEC_MOTION_CANCEL);
        }
    }
}
